Running Arch on an overclocked PC is totally fine provided that the PC is stable at the overclock settings. There are several programs available to you that will help you stress test your system and thereby the overclock levels you are attempting to achieve. The steps of overclocking a PC are beyond the scope of this article, but there is pretty inclusive guide written by graysky on the topic: [[http://www.hardforum.com/showthread.php?t=1198647 Overclocking guide]].

+

Running an overclocked PC is totally fine provided that the PC is stable at the overclock settings. There are several programs available to assess system stability through stress testing the system and thereby the overclock level. The steps of overclocking a PC are beyond the scope of this article, but there is pretty inclusive guide written by graysky on the topic: [[http://www.hardforum.com/showthread.php?t=1198647 Overclocking guide]].

−

{{note|Although you can stress test a newly overclocked system under Linux, it is strongly recommended that you do not do it. Why? You can experience data loss from the HDD depending on how your system fails in the event of an unstable overclock. Linux is less forgiving that Windows for rebooting from a hardlocked system without damage to the file system. If you insist on testing various overclocked levels under Linux, it is advisable to backup ALL important data first. Better yet is to install Arch to an old HDD and unplug your HDD(s) that carry your important data to iron out the overclock settings and arrive at a stable system.}}

+

{{Note|The linked guide is a bit dated. More contemporary guides are recommended for modern hardware.}}

−

== Stressing Memory ==

+

== Discovering Errors ==

−

A very good program for stress testing your memory is [[http://www.memtest.org/ Memtest86+]]. It is based on the well-known original memtest86 written by Chris Brady. Memtest86+ is, like the original, released under the terms of the GNU General Public License (GPL). No restrictions for use, private or commercial exist other than the ones mentioned in the GNU GPL.

+

Some stressing applications like mprime and linpack (see below) have built in consistency checks to discover errors due to non-matching results. A more general and simple method for measuring hardware instabilities can be found in the kernel itself. To use it, simply watch the output from the kernel ring buffer by this command:

+

# cat /proc/kmsg

+

+

The key error to watch for looks like this:

+

+

[Hardware Error]: Machine check events logged

+

+

The kernel can throw these errors during an mprime run before mprime itself finishes the calculate and reports the error thus providing a very sensitive method to assess stability.

+

+

== CPU Stressing Programs ==

+

These are listed in two categories: 'higher demand voltage' and 'medium demand voltage'. It is important to use some from each category to evaluate system stability. Ironically, machines can be more sensitive to selections from the 'medium demand' category than from the 'high demand' category. 'Higher demand voltage' programs demand the most vcore when run due to intense hardware usage. 'Medium demand voltage' programs do not always call for the highest vcore when running and as such can be more prone to throwing errors for systems that are undervolted relative to the clock speed requested.

+

+

Example on an overclocked i7-3770K (4.50 GHz); vcore is +0.020 V in offset mode with all powersaving features enabled.

−

You may download it from the webhost of memtest86+ [[http://www.memtest.org/#downiso here]] either as a bootable CD ISO or as an pre-compiled bootable binary. The later can be called by GRUB with a minor modification to your menu.lst to allow you to boot directly into Memtest86+ without a CD/DVDROM.

+

Idle: 0.7440 V - 0.8320 V (varies).

+

Mprime small FFTs: 1.2880 V (steady).

+

Mprime large FFTs: 1.3040 V (steady).

+

Mprime blend: 1.2960 V (steady).

+

Linpack: 1.2320 V - 1.2720 V (varies).

+

x264 encoding: 1.2320 V - 1.2720 V (varies).

+

gcc compiling: 1.2720 V (steady).

−

=== Running Memtest86+ ===

+

This machine running with a vcore of +0.005 (in offset mode) remains stable in both mprime and linpack for hours, but throws errors under both x264 and gcc after only several minutes.

−

Either download and burn the ISO to a CD and boot from it, or follow the instructions in the next section to add an entry to your GRUB boot menu. Either way when you enter Memtest86+, the application begins testing your memory without your intervention. It will run indefinitely until you stop it reporting any errors as it goes. When it has completed a number of iterations without errors or runs for an arbitrary amount of time without errors, you can pretty much call your memory "good" or "stable" at the settings you have chosen for it in your BIOS.

−

{{tip|Allowing Memtest86+ to run for >10 cycles without errors is usually sufficient.}}

+

{| class="wikitable" align="center"

−

=== Running Memtest86+ from GRUB's Bootscreen ===

+

|-

−

Either install the package {{Pkg|memtest86+}} ({{ic|pacman -S memtest86+}}) or download the pre-compiled bootable binary from the webhost above and move or copy the .bin file from the archive to {{ic|/boot/memtest86+/memtest.bin}}. Next, edit your {{ic|/boot/grub/menu.lst}} by adding something like the following entry:

| ''mprime'' || {{AUR|mprime-bin}} factors large numbers and is an excellent way to stress CPU and memory.

+

|-

+

| ''linpack'' || {{AUR|linpack}} - Linpack makes use of the BLAS (Basic Linear Algebra Subprograms) libraries for performing basic vector and matrix operations. and is an excellent way to stress CPUs for stability.

+

|-

+

|}

−

You will obviously need to change the device specification ({{ic|(hd0,2)}}) to make sense on your own system. Remember that the {{ic|(hdx,y)}} format takes its inputs starting from 0, not 1; in other words, your first hardrive is {{ic|0}} and your first partition is also {{ic|0}}. If your root partition resides on the 1st partition of the 1st HDD, then you would use the following line:

+

== Memory Stressing Programs ==

−

root (hd0,0)

+

=== Memtest86+ ===

+

Memtest86+ is a standard memory testing util and is packaged in [extra].

−

{{note|If your system uses a dedicated {{ic|/boot}} partition, then you may need to omit the preceding '/boot' from the kernel line of the above example. Your kernel line in this scenario could simply be {{ic|kernel /memtest86+/memtest.bin}}}}

+

== Stressing CPU and Memory ==

+

===Mprime (Prime95 for Windows and MacOS)===

−

== Stressing CPU and/or Memory ==

+

Prime95 is recognized universally as one defacto measure of system stability. Mprime under torture test mode will preform a series of very CPU intensive calculations and compare the values it gets to known good values.

−

A very good program for CPU and CPU/memory stress testing is [[http://www.mersenne.org/ prime95]]. There are both x86 and x86_64 version for Linux you can freely use for stress testing purposes under Linux. Prime95 under torture test mode will preform a series of very CPU intensive calculations and compare the values it gets to known good values. The theory is that if your system is sufficiently stable to get the right answers, it should be stable to most anything you will throw at it. Prime95 is pretty much recognized universally as one defacto measure of an overclocked system's stability.

−

=== Getting Prime95 ===

+

Prime95 for Linux is called {{AUR|mprime}} and is available in the AUR.

−

Prime95 for Linux is called mprime and is available in the AUR in [[https://aur.archlinux.org/packages.php?ID=6975 this package]].

−

=== Running Prime95 ===

+

{{Warning|Before proceeding, it is '''HIGHLY''' recommended that users have some means to monitor the CPU temperature. Packages such as [[Lm_sensors]] can do this.}}

−

{{Warning|Before you proceed, it is '''HIGHLY''' recommended that you have some means to monitor the CPU temperature of your system at a minimum. Packages such as [[Lm_sensors]] can do this for you!}}

−

To run prime95, simply open a shell and type "mprime"

+

To run mprime, simply open a shell and type "mprime"

$ mprime

$ mprime

−

{{note| If you're using a cpu-frequency scaler such as [[cpufrequtils]] or [[powernowd]] you will have to manually set your processor to run with its highest multiplier because prime95 uses a nice value that doesn't trip the step-up in your multiplier. If you're using Gnome this is easily accomplished with the CPU Frequency Scaling Monitor via a left-click and selection of the 'Performance' profile.}}

+

{{note| If using a cpu-frequency scaler such as [[cpufrequtils]] or [[powernowd]] sometimes, users need to manually set the processor to run with its highest multiplier because mprime uses a nice value that doesn't always trip the step-up in multiplier.}}

+

+

When the software loads, simply answer 'N' to the first question to begin the torture testing:

−

When the software loads, simply answer 'N' to the first question to begin the torture testing. The software begins with the torture test, but if you hit {{Keypress|CTRL}} + {{Keypress|C}} you can break out and return to the main prime95 menu shown here:

Main Menu

Main Menu

Line 66:

Line 95:

* In-place large FFTs (option 1) to test the CPU and memory controller

* In-place large FFTs (option 1) to test the CPU and memory controller

* Blend (option 3) is the default and constitutes a hybrid mode which stresses the CPU and RAM.

* Blend (option 3) is the default and constitutes a hybrid mode which stresses the CPU and RAM.

−

−

{{tip|If you enter modes 11, 12, or 13 you can further customize the first three options. For example, if you wish to use a maximal amount of RAM in the tests, select option 13 and manually enter 95 % of your memory as the amount to use.}}

Errors will be reported should they occur both to stdout and to {{ic|~/results.txt}} for review later. Many do not consider a system as 'stable' unless it can run the Large FFTs for a 24 hour period.

Errors will be reported should they occur both to stdout and to {{ic|~/results.txt}} for review later. Many do not consider a system as 'stable' unless it can run the Large FFTs for a 24 hour period.

Line 86:

Line 113:

Self-test 560K passed!

Self-test 560K passed!

Self-test 560K passed!

Self-test 560K passed!

−

[Sat Aug 20 11:38:05 2011]

+

...</pre>

−

Self-test 192K passed!

+

−

Self-test 192K passed!

+

{{Note|Users suspecting bad memory or memory controllers should try the blend test first as the small FFT test uses very little memory.}}

−

[Sat Aug 20 11:53:44 2011]

+

−

Self-test 640K passed!

+

=== Linpack ===

−

Self-test 640K passed!

+

Linpack makes use of the BLAS (Basic Linear Algebra Subprograms) libraries for performing basic vector and matrix operations. and is an excellent way to stress CPUs for stability. {{AUR|linpack}} is available from the AUR. After installation, users should adjust {{ic|/etc/linpack.conf}} according to the amount of memory on the target system.

−

[Sat Aug 20 12:08:51 2011]

+

−

Self-test 240K passed!

+

=== Systester (SuperPi for Windows) ===

−

Self-test 240K passed!

+

{{AUR|Systester}} is available in the AUR in both cli and gui version. It tests system stability by calculating up to 128 millions of Pi digits and includes error checking. Note that one can select from two different calculation algorithms: Quadratic Convergence of Borwein and Gauss-Legendre. The latter being the same method that the popular SuperPi for Windows uses.

−

[Sat Aug 20 12:25:09 2011]

+

−

Self-test 720K passed!

+

A cli example using 8 threads is given:

−

Self-test 720K passed!

+

$ systester-cli -gausslg 64M -threads 8

−

[Sat Aug 20 12:40:14 2011]

+

−

Self-test 288K passed!

+

== Stressing Memory ==

−

Self-test 288K passed!

+

A very good program for stress testing memory is [[http://www.memtest.org/ Memtest86+]]. It is based on the well-known original memtest86 written by Chris Brady. Memtest86+ is, like the original, released under the terms of the GNU General Public License (GPL). No restrictions for use, private or commercial exist other than the ones mentioned in the GNU GPL.

−

[Sat Aug 20 13:17:11 2011]

+

−

Self-test 480K passed!

+

=== Running Memtest86+ ===

−

Self-test 480K passed!

+

Either download and burn the ISO to a CD and boot from it, or install {{Pkg|memtest86+}} from [extra] and update GRUB which will auto-detect the package and allow users to boot directly to it.

−

[Sat Aug 20 13:32:18 2011]

+

−

Self-test 128K passed!

+

{{tip|Allowing Memtest86+ to run for >10 cycles without errors is usually sufficient.}}

Introduction

Running an overclocked PC is totally fine provided that the PC is stable at the overclock settings. There are several programs available to assess system stability through stress testing the system and thereby the overclock level. The steps of overclocking a PC are beyond the scope of this article, but there is pretty inclusive guide written by graysky on the topic: [Overclocking guide].

Note: The linked guide is a bit dated. More contemporary guides are recommended for modern hardware.

Discovering Errors

Some stressing applications like mprime and linpack (see below) have built in consistency checks to discover errors due to non-matching results. A more general and simple method for measuring hardware instabilities can be found in the kernel itself. To use it, simply watch the output from the kernel ring buffer by this command:

# cat /proc/kmsg

The key error to watch for looks like this:

[Hardware Error]: Machine check events logged

The kernel can throw these errors during an mprime run before mprime itself finishes the calculate and reports the error thus providing a very sensitive method to assess stability.

CPU Stressing Programs

These are listed in two categories: 'higher demand voltage' and 'medium demand voltage'. It is important to use some from each category to evaluate system stability. Ironically, machines can be more sensitive to selections from the 'medium demand' category than from the 'high demand' category. 'Higher demand voltage' programs demand the most vcore when run due to intense hardware usage. 'Medium demand voltage' programs do not always call for the highest vcore when running and as such can be more prone to throwing errors for systems that are undervolted relative to the clock speed requested.

Example on an overclocked i7-3770K (4.50 GHz); vcore is +0.020 V in offset mode with all powersaving features enabled.

systesterAUR Systester is a multithreaded piece of software capable of deriving values of pi out to 128,000,000 decimal places. It has built in check for system stability.

High

mprime

mprime-binAUR factors large numbers and is an excellent way to stress CPU and memory.

linpack

linpackAUR - Linpack makes use of the BLAS (Basic Linear Algebra Subprograms) libraries for performing basic vector and matrix operations. and is an excellent way to stress CPUs for stability.

Memory Stressing Programs

Memtest86+

Memtest86+ is a standard memory testing util and is packaged in [extra].

Stressing CPU and Memory

Mprime (Prime95 for Windows and MacOS)

Prime95 is recognized universally as one defacto measure of system stability. Mprime under torture test mode will preform a series of very CPU intensive calculations and compare the values it gets to known good values.

Warning: Before proceeding, it is HIGHLY recommended that users have some means to monitor the CPU temperature. Packages such as Lm_sensors can do this.

To run mprime, simply open a shell and type "mprime"

$ mprime

Note: If using a cpu-frequency scaler such as cpufrequtils or powernowd sometimes, users need to manually set the processor to run with its highest multiplier because mprime uses a nice value that doesn't always trip the step-up in multiplier.

When the software loads, simply answer 'N' to the first question to begin the torture testing:

Note: Users suspecting bad memory or memory controllers should try the blend test first as the small FFT test uses very little memory.

Linpack

Linpack makes use of the BLAS (Basic Linear Algebra Subprograms) libraries for performing basic vector and matrix operations. and is an excellent way to stress CPUs for stability. linpackAUR is available from the AUR. After installation, users should adjust /etc/linpack.conf according to the amount of memory on the target system.

Systester (SuperPi for Windows)

SystesterAUR is available in the AUR in both cli and gui version. It tests system stability by calculating up to 128 millions of Pi digits and includes error checking. Note that one can select from two different calculation algorithms: Quadratic Convergence of Borwein and Gauss-Legendre. The latter being the same method that the popular SuperPi for Windows uses.

A cli example using 8 threads is given:

$ systester-cli -gausslg 64M -threads 8

Stressing Memory

A very good program for stress testing memory is [Memtest86+]. It is based on the well-known original memtest86 written by Chris Brady. Memtest86+ is, like the original, released under the terms of the GNU General Public License (GPL). No restrictions for use, private or commercial exist other than the ones mentioned in the GNU GPL.

Running Memtest86+

Either download and burn the ISO to a CD and boot from it, or install memtest86+ from [extra] and update GRUB which will auto-detect the package and allow users to boot directly to it.

Tip: Allowing Memtest86+ to run for >10 cycles without errors is usually sufficient.